Seed Dormancy and Its Alleviation in Lovegrass Hybrids

Abstract

Weeping lovegrass, Eragrostis curvula (Schrad.) Nees, was introduced to the Americas for soil conservation. It is a useful forage only if intensively managed. Apomictic lovegrass hybrids, developed from introductions with higher forage quality, need to be evaluated in multiple environments to determine their potential. Studies were to be established in Argentina the same year seed was produced in the USA. This could only be accomplished if seed dormancy was low. Seed of experimental strains were harvested in 1993 and 1994 at Temple, TX. Germination and/or emergence experiments were conducted in alternating light‐dark and dark environments. A mixture of 2‐chloroethanol and sodium hypochlorite (CHL) was evaluated a dormancy breaking treatment. The lovegrass hybrids studied in these experiments varied widely in germination, because of seed dormancy. This dormancy was largely dissipated after 0.75 yr of storage in a temperature‐controlled laboratory. Thus, this post‐harvest dormancy is short‐lived compared with that of ‘A‐68’ lehmann lovegrass, Eragrostis lehmanniana Nees. Absence of light during germination usually inhibited germination, but in a few genotypes it promoted germination. Seed treatment with CHL compensated for absence of light. Effects of CHL on emergence did not decrease with time, but the difference between treated and untreated seed decreased as the post‐harvest dormancy declined with seed ageing. Concerns about obtaining adequate plants for establishment of plots in South America the same year seed was harvested were valid. Treatment of seed with CHL was a rapid, easy, and effective procedure for breaking seed dormancy in E. curvula and in E. lehmanniana and for obtaining the numbers of plants required for evaluation experiments. However, CHL is toxic and should only be used for seed treatment in laboratories where human exposure to the chemical can be controlled.